Historical weather data, all-time temperature records, and monthly climate averages for St. Charles, IL. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 5 in St. Charles runs cool, with a typical high of 55° and a low dipping to 33°. The date has seen a 56-degree swing in recorded history — from a balmy 76° in 2005 down to a bitter 20° in 2016. There's about a 1-in-3 chance of rain, but snow is off the table.
St. Charles plays it to the extremes — the thermometer has hit 100° in July and cratered to -29° in January, a 129-degree range over the station's history. The wettest single day on record dumped 6.02 inches on September 13, 2008, enough to make any Fox River resident nervous.
Summer is the clear sweet spot, with highs peaking around 84–85° in mid-July before gradually easing into a pleasant fall. Winters are serious — January highs average just 31°, and the coldest week of the year bottoms out around the 15th. If you're watching the rain, hold off until May, when weekly precipitation averages top out at 1.35 inches.